Recently, various electronic devices such as a digital camera and a mobile phone have been increasingly equipped with a memory card socket structure for allowing a small-sized storage medium (hereinafter, simply referred to as ‘memory card’) such as a Mini SD Memory Card (Registered Trademark) to be inserted thereinto or taken out therefrom.
Such a memory card socket structure typically has a plurality of contact terminals (contacts) making a contact with terminals (I/O contact surfaces) of a memory card corresponding thereto when the memory card is inserted in a card accommodating portion of a memory card case installed at an electronic device, wherein transception of data and signals is carried out between the memory card and the electronic device via the contact terminals (see, for example, Japanese Patent Laid-open Application No. 2004-119148, specifically Pg. 4 and FIG. 18: Reference 1).
In Reference 1, the number of the contact terminals is determined depending on the number of the terminals (electrodes) of the memory card. A proximal end of each contact terminal is fixed at a contact block arranged at a rear side of the card accommodating portion, while its distal end is projected toward a front side of the card accommodating portion to make a contact with a corresponding one of the terminals of the memory card.
Further, the contact terminals include shorter terminals and longer terminals so as to be corresponded to set positions of the terminals (electrodes) of the memory card.
In the configuration of the above conventional memory card socket structure, however, if the degrees of bending of the shorter terminals and longer terminals are set identical, contact surface pressures between the longer terminals and the corresponding memory card terminals can be lowered relative to contact surface pressures between the shorter terminals and the corresponding the memory card terminals. In addition, since the longer terminals are more likely to be affected by a dimensional difference or the like, there is a high likelihood that the longer terminals would suffer a bending deformation or a buckling deformation caused by a thermal stress or a force exerted thereto when inserting the memory card into the socket structure. Such a deformation would in turn cause a reduction in the contact surface pressures between the longer terminals and the memory card terminals, resulting in a contact failure therebetween.
Moreover, in case of the memory card case being formed of a metal conductor, distal ends of the bent longer terminals might come into contact with the case, thus being subject to a short circuit.